• Evolution of wheat spikes since the Neol

    From ScienceDaily@1:317/3 to All on Thu Feb 2 21:30:22 2023
    Evolution of wheat spikes since the Neolithic revolution

    Date:
    February 2, 2023
    Source:
    University of Barcelona
    Summary:
    Around 12,000 years ago, the Neolithic revolution radically changed
    the economy, diet and structure of the first human societies
    in the Fertile Crescent of the Near East. With the beginning of
    the cultivation of cereals -- such as wheat and barley -- and the
    domestication of animals, the first cities emerged in a new social
    context marked by a productive economy. Now, a study analyses
    the evolution of wheat spikes since its cultivation began by the
    inhabitants of ancient Mesopotamia -- the cradle of agriculture --
    between the Tigris and the Euphrates.


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    FULL STORY ========================================================================== Around 12,000 years ago, the Neolithic revolution radically changed the economy, diet and structure of the first human societies in the Fertile Crescent of the Near East. With the beginning of the cultivation of
    cereals - - such as wheat and barley -- and the domestication of animals,
    the first cities emerged in a new social context marked by a productive economy. Now, a study published in the journal Trends in Plant Science
    and co-led by the University of Barcelona, the Agrotecnio centre and the University of Lleida, analyses the evolution of wheat spikes since its cultivation began by the inhabitants of ancient Mesopotamia -- the cradle
    of agriculture in the world - - between the Tigris and the Euphrates.


    ==========================================================================
    The authors of the study are Rut Sa'nchez-Bragado and Josep Llui's Araus- Ortega, from the UB Faculty of Biology and Agrotecnio-UdL; Gustavo
    A. Slafer, ICREA researcher at the UdL School of Agrifood and Forestry
    Science and Engineering, and Gemma Molero, from the International Maize
    and Wheat Improvement Center in Mexico, currently a researcher at KWS
    Seeds Inc.

    A cereal that changed human history The cultivation of wheat -- a grass
    that became basic food -- represented a turning point in the progress
    of human civilisation. Today it is the world's most important crop in
    terms of food security, but EU data warn that the impact of climate
    change could significantly increase its price and modify its production
    process in certain areas of the world.

    Throughout the domestication process of wheat, the plant phenotype has undergone both rapid (within a few hundred years) and slow (thousands
    of years) changes, such as the weakening of the rachis, the increase in
    seed size, and the reduction or disappearance of the awns. In particular,
    awned and awnless wheat varieties are found all over the world, although
    the latter tend to be abundant in regions with arid climates, especially
    during the final stages of cultivation in late spring, a condition
    typical of Mediterranean environments.

    "It is important to conduct studies that show which wheat varieties are
    best adapted to different environmental growing conditions, especially in
    a context of climate change. Studying the past retrospectively can give
    us an idea of the evolution of wheat cultivation over the millennia since agriculture appeared in ancient Mesopotamia," says Rut Sa'nchez-Bragado,
    first author of the study, who got a PhD at the UB.

    "Awns are organs of the spike that have traditionally been associated
    with the plant's adaptations to drought conditions," says Josep Llui's
    Araus, professor at the Department of Evolutionary Biology, Ecology and Environmental Sciences of the Faculty of Biology.

    "However, archaeological and historical records show that the wheat spike
    has existed predominantly with awns for more than ten millennia after
    the domestication of wheat. It is not until the last millennium that
    evidence shows in many cases the absence of awns, indicating a selection
    by farmers - - probably in an undirected way -- against this organ,"
    stresses Araus, one of the most cited authors in the world according to Clarivate Analytics' Highly Cited Researchers (2022).

    "The role of wheat awns in their performance remains controversial despite decades of studies," says researcher Gustavo A. Slafer, corresponding
    author of the study.

    Spike awns: beneficial for the plant? Is the presence of awns on the
    spike beneficial for the plant and the crops? Although there is no
    scientific consensus, "everything suggests that in conditions where
    the plant does not suffer from water stress, the extra photosynthetic
    capacity of the awns does not compensate for other potential negative
    effects (reduced susceptibility to fungal diseases, limitation in the
    total number of large ones that an ear supports, etc.)," says Araus.

    "However, in wetter climates the awns accumulate moisture and can promote
    the spread of diseases," says Rut Sa'nchez-Bragado. "So, as the world's population is continuously growing, it is necessary to investigate the
    role of the awned spikes in the changing conditions of our climate in
    order to meet the world's demand for a primary food commodity such
    as wheat." In arid conditions, the spikes -- including the awns --
    "have better physiological characteristics than the leaves. In addition,
    the awns allow the light captured by the crop to be more diffused,
    which facilitates a better distribution of light energy and allows the
    crop to photosynthesise more.

    Therefore, in arid conditions, the awns can still be beneficial for the
    crop, or at most, neutral," concludes Professor Josep Llui's Araus.

    * RELATED_TOPICS
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    ========================================================================== Story Source: Materials provided by University_of_Barcelona. Note:
    Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Rut Sanchez-Bragado, Gemma Molero, Jose' L. Araus, Gustavo
    A. Slafer.

    Awned versus awnless wheat spikes: does it matter? Trends in Plant
    Science, 2022; DOI: 10.1016/j.tplants.2022.10.010 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2023/02/230202153525.htm

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